[Review] Request from 'vlewin' @ 'SUSE/connect/review_140630_extend_yast_wrapper_to_include_activated_'

Please review the following changes:
  * 284bb3c Merge pull request #124 from SUSE/review_140630_fix_status_call_regression
  * 42df4ae add product_activated? and system_activated? methods to the YAST wrapper class
  * 0d4c87b introduce activated? and adapt registered? method
  * 1bef3ed rename registered? to announced?
  * 509b9d5 Update package files
  * 2202147 Fix status call regression in case of free products

This is still not _quite_ correct. Technically, this is closer to `credentials?`. Whether SCC actually knows of this system is not 100% sure. Let's assume the system gets deleted from SCC's UI, then it's no longer `announced?`, but still has `credentials?`. I believe renaming this method would makes this circumstance clearer. I'd love to have a third opinion though. @wstephenson ? @digitaltom ? Anyone?